In her chemistry class, Ashley took 4 quizzes. Her scores were 75, 77, 86, and 78. What was her average score on the quizzes?
Solution: The average is the sum of her scores divided by the number of scores. There are 4 scores and their sum is $75 + 77 + 86 + 78 = 316$ Her average score is $316 \div 4 = 79$.